In the use of a resilient link apparatus, it is desirable to provide separate means each imparting resiliency to a normally rigid control system in a respective one of first and second directions for convenience in assembly and use of differing force limits for resiliency in a respective direction.
The invention relates to first means, for example, a first spring, for moving a first member in response to exerting a first force in a first direction on said first member. Said first means thereby provides resiliency in response to the resilient link being under tension. Second means, for example, a second spring, is provided for moving a second member in response to a second force in a second direction on said second member. Said second means provides resiliency in response to the resilient link being under compression. The resiliency results from relative movement of the first and second members.
U.S. Pat. No. 2,400,633, which issued on May 21, 1946, to Derungs, discloses a resilient coupling device having a single spring means to control resiliency in response to forces of equal magnitude applied in tension and compression on the coupling device.
U.S. Pat. No. 3,343,858, which issued on Sept. 26, 1967 to Rice, discloses a resilient link having a single spring means providing resiliency in response to one of the components connected to the link not being movable by a predetermined force.
A resilient link apparatus is generally used on cable or arm control systems to prevent damage to the system from the application of excessive force through the control cable or arm. For example, a control cable is connected at one end to a control valve. A control lever is connected at the other end. The lever is used to push or pull the cable and change control positions of the valve. Push-pull cable assemblies generally require fine adjustments to synchronize movement of the control lever with that of the valve. Travel stops are necessary in each direction of travel of the control lever to prevent over travel of system components owing to application of excessive force to the control handle.
The fine adjustments necessary to synchronize the lever movement relative to the stops and full travel of the valve are time consuming and sometimes change during operation of the vehicle, especially under harsh operating conditions. A resilient link is incorporated into the controls to reduce the importance of fine adjustments and close tolerances in the stops and lever control.
The resilient link normally transmits forces rigidly through the control cable. However, if the force on the cable reaches a preselected magnitude, the resilient link provides relative movement of cable portions to prevent damage in response to the excessive force. Heretofore, resilient link construction has not permitted convenient servicing of components to change the operating characteristics of the link. The use of separate force limits of resiliency in tension and compression on the cable has also been unavailable. This is needed to accommodate use of, for example, a spring assisted valve in which the force exerted through the cable to move the valve in one direction is different from the force moving the valve in the opposed direction.
Therefore, it is desirable to provide first and second means each adjustable and controlling the deflection on the resilient link in response to a respective one of applied force in tension and in compression on the link and control system.